/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.log4j;

import org.apache.log4j.spi.ThrowableRenderer;

import java.io.StringWriter;
import java.io.PrintWriter;
import java.io.LineNumberReader;
import java.io.StringReader;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.util.ArrayList;

/**
 * Default implementation of ThrowableRenderer using Throwable.printStackTrace.
 * 
 * @since 1.2.16
 */
public final class DefaultThrowableRenderer implements ThrowableRenderer {
	/**
	 * Construct new instance.
	 */
	public DefaultThrowableRenderer() {

	}

	/**
	 * {@inheritDoc}
	 */
	public String[] doRender(final Throwable throwable) {
		return render(throwable);
	}

	/**
	 * Render throwable using Throwable.printStackTrace.
	 * 
	 * @param throwable
	 *            throwable, may not be null.
	 * @return string representation.
	 */
	public static String[] render(final Throwable throwable) {
		StringWriter sw = new StringWriter();
		PrintWriter pw = new PrintWriter(sw);
		try {
			throwable.printStackTrace(pw);
		} catch (RuntimeException ex) {
		}
		pw.flush();
		LineNumberReader reader = new LineNumberReader(new StringReader(
				sw.toString()));
		ArrayList lines = new ArrayList();
		try {
			String line = reader.readLine();
			while (line != null) {
				lines.add(line);
				line = reader.readLine();
			}
		} catch (IOException ex) {
			if (ex instanceof InterruptedIOException) {
				Thread.currentThread().interrupt();
			}
			lines.add(ex.toString());
		}
		String[] tempRep = new String[lines.size()];
		lines.toArray(tempRep);
		return tempRep;
	}
}
